Gas Tungsten Arc Welding is a well known metal joining technique. In certain applications, space limitations preclude the use of conventional GTAW weldheads. In these cases, alternative metal joining techniques have heretofore been required. Such applications include aerospace, semiconductor fabrication equipment and instrumentation. Alternative metal joining techniques include brazing, hand welding and use of mechanical fittings.
Brazing tends to be a more expensive process than welding because of the consumption of a costly braze material. In certain critical applications, such as the joining of space satellite fuel lines, a gold alloy braze material may be required. Furthermore, in most cases, brazing involves use of a flux material which requires post-joining clean up. In some cases, brazing may be done in an oven. However, this precludes in-position joining and, therefore, components to be welded must be prefabricated before final assembly, thereby placing constraints on the assembly sequence. In addition to the foregoing disadvantages of brazing, brazing may be precluded in cases where the braze material is chemically reactive with fluid to be transported inside the tubing.
Hand welding is a versatile process that can accommodate close working clearances, however, the quality of the welded joint is highly dependent upon individual craftsmanship. Hand welding is therefore not a desirable technique in critical applications where consistent repeatability is required
Mechanical fittings are also dependent upon individual operator technique with respect to mating and torquing of the fittings. Repeatability is again a problem, but less so than with manual welding. Generally speaking, mechanical fittings are more prone to failure due to mechanical vibration than is a welded joint.
A need therefore exists for a means of producing welded joints of high repeatable quality under conditions where the working clearances preclude the use of conventional weldheads. The present invention provides a weldhead of a much smaller size than those heretofore available and with which highly repeatable welded joints in tubing may be achieved.